I. Field of the Invention
The present invention relates generally to a power transmission system with reduced electromagnetic interference and, more particularly, to the power transmission between a power inverter and a battery in an electric or hybrid electric automotive vehicle.
II. Description of Related Art
New developments and advancements in the automotive industry are primarily driven by new and improved electronic components in the automotive vehicles. These new developments include, for example, vehicle navigation systems, infotainment equipment, safety equipment, and the like.
In order to ensure the functionality of the increasingly complex electronic systems in automotive vehicles and also to minimize the negative impacts of the automotive system on external systems, electromagnetic capability (EMC) has become an increasing concern for the automotive vehicles. This is particularly true in hybrid electric vehicles and electric vehicles where high voltage and high current switching is required in order to power the vehicle.
In particular, hybrid electric vehicles and electric vehicles (hereinafter collectively referred to as “electric vehicles”) typically use a power inverter which switches high current and voltage and provides the necessary power outputs to the electric motor or motors utilized to propel the vehicle. In order to supply the electrical power to the power inverter for ultimate distribution to the electric vehicle motor or motors, the electric vehicle includes a high capacity electric battery.
Conventionally, a pair of elongated conductors is used to electrically connect the battery to the power inverter in an electric vehicle. The electric battery is usually spaced from the power inverter so that the electrical conductors between the power inverter and the battery extend along the electrically conductive vehicle chassis.
Due to impedance mismatching of the electrical conductors and their connection with both the power inverter and the battery, common mode electric currents are generated along both conductors. These common mode electric currents, in turn, generate electromagnetic interference (EMI) which may interfere with the electrical components of the vehicle electrical system. For example, the common mode electrical currents generated on the electrical conductors between the power inverter and the battery are known to generate electrical noise which interferes with the electrical system of other electrical components of the vehicle, such as the radio or other infotainment device. As such, the reduction of electrical noise from these common mode currents has become a high priority in the design of electrical systems for automotive vehicles and especially electric vehicles where the generation of EMI is inherently more challenging than nonelectric automotive vehicles.